How do I check if multiple values exists in database?

Question

I have a list of email addresses in the Java code and I would like to check if any of these already exists in the MySQL database.

For example:

1. [email protected]
2. [email protected]
3. [email protected]

I want to know if any of the above email ids is already present in the table, and if they do, I would like to pull or separate them out.

I am not sure how to achieve this. Should I try this in Java or use SQL to achieve the desired result?

Answer 1

Here are different solutions that will help you achieve what you want

• This SQL expression will tell you if an email exists or not:

  SELECT IF (COUNT(*) > 0, 'Exist', 'Not exist')
  FROM email_table 
  WHERE email = '[email protected]';
  

• If you just want the number of occurrences you can do this:

  SELECT COUNT(*)
  FROM email_table
  WHERE email = '[email protected]';
  

• If you want to check for multiple values at a time you can do this:

  SELECT COUNT(*)
  FROM email_table
  WHERE email IN ('[email protected]', '[email protected]');
  

• If you want to see which IDs are found:

  SELECT email
  FROM email_table
  WHERE email IN ('[email protected]', '[email protected]');